As described in Tokkai 2000-319366, a polyester with a fluorene residue is already known. This polyester has excellent heat-resistance and transparency, high refractive index, low birefringence and low water absorptivity, and is therefore suitable as an optical instrument material. However, as there was almost no overlap of fluorene residues, it was difficult to make it express electrical characteristics using the properties of n-conjugated electrons.
It is also known that by adding an electron acceptor compound or an electron donor compound to a polymer material with a π-conjugated group such as polyacethylene or polyfluorene, a material exhibiting charge transport qualities will be obtained. However, as such a material is degraded by water or oxygen, there was a problem as to its stability as a material exhibiting charge transport qualities.